https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109922
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jiang An from comment #2) > The requirements was removed by N0958 > (https://www.open-std.org/jtc1/sc22/wg21/docs/papers/1996/N0958.pdf), and > then setfill and its friends are only required to be usable with operator<<. I don't think the 27-652 change from N0958 was applied to the draft, but 27-651 in https://www.open-std.org/jtc1/sc22/wg21/docs/papers/1996/N0964.pdf changed setfill.
